Wood-grinder.



PATENTED FEB. 2'7, 1906.

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T. H. SAVlEIRY.A WOOD GRINDER.

APPLICATION FILED APR. 18, 1902.

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THOMAS H. SAVERY, OF IVILMINGTON, DELAWARE.

WOOD-GRINDER.

Specification of Letters Patent.

Patented Feb. 27, 1906.

Application tiled April 18, 1902t Serial No. 103,654.

To all w/wm, t may concern:

Be it known that I, THOMAS I-l. SAvniiY, a citizen of the United States, residing at Wilmington, county of Newcastle, and Statel of Delaware, have invented certain new and useful Improvements in Vood -Grinders, fully described and represented in the following specification andI the accompanying drawings, forming a part of the saine.

This invention relates to improvements in n'iachines generally known as "wood-grind- 01s,y which are used for grinding wood and in the manufacture of an article of commerce commerce known as ground-wood pulpf These wood-grinders consist of a revolving grindstone secured to a suitably-driven shaft by clamps or washers connected to the shaft and frictionally engaging opposite sides of the stone. in diameter than the opening in the stone through which it passes', (to allow for expansion and contraction of the shaft and stone,) and the `clamps or washers are connected to the shaft and held in frictional engagement with the sides of the stone by right and left hand straight screw-threads formed upon the shaft and engaging correspondinglythreaded openings in the clamps or washers. When in operation, the stone is partially submerged in water and has water poured upon it, and the wood to be ground is held against the periphery of the stone by suitable pressing means. The stones usedin these woodgrindersare very large and hiavy and are, moreover, subjected to great pressure by the wood to be ground and by the means employed for pressing the wood against the periphery of the stone. Because of this, in starting up slip will occur between the'shaft on the one hand and the stone and its clamps or washers ont-he other, with the result that the right and left hand screw-threads on the shaft working in the correspondingly-threaded openings in the clamps or washers will move the clamps or washersinwardly toward each other, and thus tighten their hold upon or frietional engagement with the stone and.

at the same time bind or lock them more 'lirlnly or rigidly to the threaded portion of the shaft. This slip occurs not only in starting up, but also occurs occasionally during the operation of the grinder, and whenever it does occur the clamps or washers are moved in 'ardly toward eachother, as ust described,

The shaft is considerably smallerA and the screw-threads upon 4the washers or clamps are caused to bind or interlock still more firmly or rigidly with the right and left hand threads upon the shaft. of this tightening or binding action between the screw-threads on the shaft and those on the clamps or washers the clamps or washers in time become so firmly united to or intorlocked with the threaded portions of the shaft that it is always a matter of great dilli-4 c'ulty, involving the expenditure of considerable time and labor to unscrew the clamps or washers when it is desired to remove a stone because of wear and for other reasons and to replace it with another. In fact, it has often occurred in wood-grinders of this kind as heretofore constructed that the clamps o1' washers bec-ame so firmly united to the threaded portions of the shaft, because of this tightening or binding action, as to render it impossible to uuscrew the clamps or washers without strippingo'll and destroying the threads on the washers and on the shaft, thus rendering the washers and shaft unl-it for use. This diiliculty in removing the washers or clamps is increased by the fact Because that, as before stated, the stones are while ope erating partially immersed in water and have Water poured upon them, with the result that in time the threads on the shaft and lwashers or clamps become covered with rust and other foreign mat-ter to such an extent as to prevent or render dillicult the unsc'rcwing of thc clamps or washers. This difficulty I have discovered may be remedied by connecting the clamps of the washers with thc shaft indirectly, as by intcrposing a threaded sleeve' .or bushing between the clai'n'psor washers and'the shaft instead of connecting them directly to the shaft, as heretofore,'andso"connecting the clamps or washers with'the shaft by means of an interposed member constitutes the main feature oll the present inven` tion. f

The present invention also embodies other features, which will be hereinafter referred to and particularly pointed out in the claims.

In the accompanying drawings, Figure l is a front view, partly in section, of a woodgrinder embodying the features of the present invention in their preferred form, the clamps or washers being connected with the shaft by tapering screw-tllreads and having sleeves or bushings interposed between them ing in the stone a, which opening is somef their inner ends with shoulders, against which VThese threads on the shaft and on the washand the shaft. Fig. 2 is an end vlew of the same. Fig. 3 is a-modification of Fig; '1,' which will be hereinafter described.

Referring to said-` drawings, a represents the grindstone, and b its shaft, which is driven from a suitable source of power. (Not shown.) The shaft b passes through an openwhat larger in diameter than the shaft to permit. expansion and contraction of the shaft and stone while in operation. The stone c is connected to shaft b by a pair of washers or clamps c, which frictionally engage opposite sides of the stone and which in turn are screwthreaded to'the shaft I) either directly or indirectly, as hereinafter described.

In wood-grinders as heretofore constructed the shaft b has been provided with right and left hand threads d, which engaged directly with corresponding threads on the washers c.

ers c were straight, like the threads d on shaft in the present case,'and, as before stated, the washers under the tightening action of the threadson the shaft and because also of the formation of rust on such threads became so firmly and rigidly united to the shaft that it was at all times difficult and sometimes impossible without destroying. the threads on the washers and on the shaft to unscrew the washers from the shaft. In the different structures shown in the present case tapering screw-threads are employed for connecting the clamps or washers and the shaft in coinbination with'the feature of the present invention of interposing a-sleeve or bushing between the washers or clamps and the shaft. .It will bc'understood, however, that this feature of the invention may be used to advantage independently of the tapered threads-- that is to say, in a structure in which the threads are not tapered, but straight, as in the prior art.

Fig. 1 shows a sleeve or bushing inter-l posed between the washer c and the shaft,- and the screw-threads e on the washers in this case are tapered, as shown, in opposite directions and engage correspondinglytapered exterior threadsf upon sleeves g, which are provided with straight interior threads h, engaging the straight threads d on shaft b. These sleeves g are preferably provided at the washers abut when they are screwed into position upon the sleeves. The threads (Z are, as before stated, right and left hand, and when the shaft rotates in the direction of the arrow, Fig. 1thcy tend, if slip occurs between the shaft and the sleeve g, washers c, and stone a, to move the sleeves g and washyerably lessened. A

ers inwardly toward each other, and thus to tighten the grip of the washers upon the l stone. 'The threadsf on sleeves q are also right and left hand, so that should slip occur between the sleeves gand washerscthe former i chine, as before stated, takes place on start ing up and also at times during the operation of the grinder, and with the old construction of a direct connectionof the clamps or washers with the shaft by means of straight screwthreads the `unscrewing of the washers is made extremely difficult or practically i1 npossible without attendant injury or destruction of the shaft or washers. By providing the interposed sleeves or bushings g, onto which the clamps or washers are screwed and which in turn are screwed onto the shaft, the difficulty of unscrewing the washers is practically avoided. This advantageous result is due partly to the fact that the increased diameter of the exterior screw-thread on the bushing over that on the shaft results in a greatly-increased area of surface contact be-v tween the washer and the bushing over that existing between the washer and shaft when Ithe washer is screwed directly onto the shaft, and this increased area of surface contact results in a corresponding decrease i-n the pressure per s uare inch, and the binding action between t 1e two parts thus inengagement, and conse uently the resistance to the unscrewing of the washers, is thus very considfurther advantage in providing such interposed bushing is that when such bushing is used, even though the screw connection between the bushing and either the shaft or the washer should become immovably fast, yet there will always be the chance of the other connection remaining sufficiently free to permit of unscrewing. The bushings or sleeves g may also be, and ,preferably are, split, as shown in Fig. 2, so that when the washers have been removed from the sleeves the sleeves may then be readily .unscrewed Providing a tapering thread between the shaft and the washer also aids in overcoming the difficulty in unscrewing the washer, since as the threads taper off in the direction in which the washer is moved in unscrewing it when the washer has been once started it will be a comparatively easy matter to complete the operation of unscrewing.

' A construction, such as shown in Fig; 1, in which straight threads are provided between the shaft and the bushings has the advantage that with such a construction shafts now in use in wood-grinders may be retained without change, tl'lejoushings being` screwed onto the straightscrew-threads already on such shafts. Tapering threads may, h0w ever, if desired, be provided between the shaft and the bushings, as shown in Fig. 3, in which `ligure the threads between the bush- IOO IIO

ings andV the washers are also shown as taposed between the sides of the stone and the innerfaces of the washers c annular strips h', of wood or other compressiblematerial.

What is claimed .is-`

1. A grinder comprising a shaft, a member connected with the shaft by a screw-thread and movable by such screw-thread along the shaft to,increase the clamping pressure as the latter rotates, and a stone-clamping device connected with said member by a screwthread, one of said screw-threads being tapered, substantially as described. v

2. A grinder comprising a shaft, a member connected with the shaft by a screw-thread and movable by such screw-,thread along the shaft to increase the clamping pressure as the latter rotates, and a stone-clamping device connected with said member by a tapering screw-thread, substantially as described.

3. A grinder comprising a shaft, a member connected with the shaft by a screw-thread and movable by such screw-thread along the shaft toincrease the clamping pressure as the latter rotates, and a stone-clamping device connectedv with said member by a tapering screw-thread, said member being split, substantially as described.

4. A grinder comprising a shaft, a member connected with the shaft by a straight screwi thread and movable by such screw-thread along the shaft to increase the clamping pressure as the latter rotates, and a stone-clamping device connected with said member by a tapering screw thread, said member being split, substantially as described.

5. A grinder comprising a shaft, twomembers connected with the shaft by right and left hand screw-threads and movable by such screw-threads along the shaft and toward each other as the shaft rotates, and two stoneclamping devices connected with said mem# bers by screw threads, one of the screwthreads for cach clamping devicebeing tapered, substantially as described.

6. A grinder comprising a shaft, two members connected with the shaft by right and left hand screw-threads and movable by such screw threads along the shaft and toward each other as the shaft rotates, and two stoneclamping devices connected with said members bytapering screw-threads, substantially as described.

7 A grinder comprising a shaft, two members connected with the shaft by right and left hand screw-threads and movable by such screw-threads along the shaft and toward each other as the shaft rotates, and two stoneclamping devices connected with said members by tapering screw-threads, said members being split substantially as described.

8. A grinder comprising a shaft, a member connected with the shaft by a screw-thread, and movable by such screw-thread along the shaft to increase the clamping pressure as the latter rotates, and a stone-clamping device connected with said member by a screwthread, substantially as described.

9. A grinder comprising a shaft, two members connected with the shaft by right and left hand screw-threads and movable by such screw-threads along the shaft and toward each other as the shaft rotates, and two stoneclamping devices connected with said mem bers by screw-threads, substantially as described.

10. A grinder comprisingl a shaft, a member connected with the shaft by a4 screwthread and movable by such screw-thread along the shaft to increase the clamping pressure as the latter rotates, and a stone-clamping device connected with said member by a screw-thread, said member being split, substantially as described.

In testimony whereof I have'hereunto set my hand in the presence of two subscribing witnesses.

` THOMAS H. SAVERY.

/Vitnesses 1 T. F. KEHOE, J. A. GRAVES. 

